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At least 739 records · Page 41Linked to original sources
PubMed1990

Retention of vital dyes correlates inversely with the multidrug-resistant phenotype of adriamycin-selected murine fibrosarcoma variants.

Retention of the vital dyes rhodamine 123 (R-123) and hydroethidine (HET) correlates inversely with the multidrug resistant phenotypes of the adriamycin (ADM)-selected variants of a uv-induced murine fibrosarcoma cell line (UV-2237M). The differential affinity of these dyes for specific cellular organelles makes them unique compounds for studies of cellular transport. HET enters viable cells freely, is dehydrogenated to ethidium bromide (EtBr), and is subsequently accumulated in the nucleus. Viable cells are impermeable to extracellular EtBr, facilitating kinetic analysis of the efflux of intracellular EtBr. We found that the metabolite EtBr was rapidly cleared by ADM-resistant but not by ADM-sensitive cells. R-123 has a high affinity to mitochondria. Our results show that ADM-sensitive cells retain R-123 whereas the ADM-resistant cells do not. The clearance of both R-123 and EtBr from these cells was inhibited by verapamil. Therefore, R-123 and HET may be considered MDR-associated compounds useful in studying the MDR phenotype of cancer cells. Previously we reported a direct correlation between the level of activity of the calcium- and phospholipid-dependent protein kinase (protein kinases C) and ADM resistance in UV-2237M variant lines. In this report, we demonstrate a direct correlation between cellular calcium and MDR in these cells. Although chelation of extracellular calcium by EDTA did not alter the fluorescence profile of R-123 of the various cell lines, treating the ADM-resistant variants with verapamil restored cellular calcium to the same level as that of the parental cells and, at the same time, retarded the facilitated efflux of R-123 and EtBr and partially reversed cancer cell resistance to ADM.

Animals↗
PubMed1986

Plasminogen activators catalyse conversion of inhibitor from fibrosarcoma cells to an inactive form with a lower apparent molecular mass.

Purified approximately 54 kDa plasminogen activator inhibitor from human fibrosarcoma cells was converted to an inactive form with slightly higher electrophoretic mobility by incubation with catalytic amounts of urokinase-type or tissue-type plasminogen activator. Serine proteinase inhibitors and a monoclonal antibody against urokinase-type plasminogen activator inhibited the conversion, indicating that it was caused by plasminogen activator-catalyzed proteolysis. These findings represent the first demonstration of a well-defined protein apart from plasminogen, constituting a substrate for plasminogen activators.

Cell Line↗
PubMed1986

Immunomodulating activities associated with the cytosol fraction of a 3-methylcholanthrene-induced rat fibrosarcoma--II. Association with polyamine complexes.

This paper characterizes the molecular nature of the factors present in cytosol from F-344 rat McFiFi2(s) fibrosarcoma cells (FiCF) which mediate inhibition of PHA-induced lymphoproliferative responses. These are polyamines (spermine/spermidine) conjugated to different protein carriers. Interaction of these complexes with polyamine oxidase (PAO) present in fetal calf or rat serum is responsible of the suppression observed.

Animals↗
PubMed1979

Preparation of antigenically active membranes from solid murine lymphomas and fibrosarcomas.

Plasma membrane preparations were obtained from solid lymphosarcomas and fibrosarcomas by disrupting the tissues with a mechanical press. The subcellular fractions were isolated by differential centrifugations and examined by electron microscopy. The membrane-enriched fractions were also assayed for protein content and analyzed in SDS-polyacrylamide gel electrophoresis; a fairly good reproducibiltiy was found comparing different membrane preparations derived from the same tumor. The H-2 antigenic activity of the different membrane preparations was demonstrated in vitro by the inhibition of the C'-dependent 51Cr-release assay using monospecific H-2 alloantisera. The specificity of the assay was ascertained by the lack of inhibition of unrelated monospecific H-2 alloantisera and by a dose-response relationship between the amount of added membranes and the observed inhibition. The immunogenicity of the membranes was assessed in vivo by immunizing allogeneic mice that developed anti-H-2 alloantibodies. The possible mechanisms of the tissue disruption by the press are also discussed.

Animals↗
PubMed1980

A rapid method for assessment of a macrophage chemotactant produced by SaD2 fibrosarcoma cells in vitro.

A new rapid method for assessing murine macrophage chemotaxis was developed using peritoneal exudate cells labeled with [5,6-3H]uridine in modified Boyden chambers with double polycarbonate filters. The method gave positive results with endotoxin-treated mouse serum and with serum-free culture supernatant of the DBA/2 SaD2 fibrosarcoma. These results correlated with results obtained with conventional microscopic assessment of chemotaxis. Using this method, the SaD2 supernatant was shown to be chemotactic rather than chemokinetic.

Animals↗
PubMed1994

Mechanism of inhibitory actions of minocycline and doxycycline on ascitic fluid production induced by mouse fibrosarcoma cells.

Semisynthetic tetracyclines (TCNs) are used for the management of malignant pleural effusions as sclerosing agents. However, their precise mechanism of actions are uncertain. In the present study, the mechanism of inhibitory effects of minocycline (MINO) and doxycycline (DOXY), on the accumulation of ascitic fluid induced by mouse fibrosarcoma (Meth-A) cells were investigated using male mice. Meth-A cells inoculated intraperitoneally elicited 2.5-4 ml of bloody ascites 10 days after implantation. The production of ascitic fluid was suppressed in a dose-related manner by daily intraperitoneal injections of MINO or DOXY, whereas vehicle (normal saline with 0.01N HCl) did not exert a significant effect. The inhibitory activity of these two substances was quite similar; one mg/mouse of MINO or DOXY inhibited the accumulation of fluid by 87% and 84%, respectively. The survival rate of Meth-A-bearing mice treated with MINO or DOXY was higher than that of the controls. Macroscopic examination of the peritoneal cavity did not reveal any obvious effects, such as adhesions, in mice treated with either MINO or DOXY. In vitro studies showed that MINO and DOXY suppressed Meth-A cell growth with IC50s of 5 microM and 8 microM, respectively. Maximal suppression (95%) was achieved at MINO and DOXY concentrations of 25 microM. The above observations suggest that MINO and DOXY inhibit the accumulation of ascites by a direct effect on Meth-A cell growth. Therefore, it appears that TCNs injected into the pleural cavity to manage malignant effusions in man exert their activity, at least in part, by suppressing malignant cell growth.

Animals↗
PubMed1989

Primary bronchopulmonary fibrosarcoma of childhood and adolescence: reassessment of a low-grade malignancy. Clinicopathologic study of five cases and review of the literature.

In children, primary tumors of the lung constitute a unique subset of quasineoplastic and unequivocally neoplastic lesions whose benign or malignant potential is not always predictable on the basis of morphologic findings. One such neoplasm in the latter category is the primary bronchopulmonary fibrosarcoma (PBPF). This clinicopathologic, ultrastructural, and immunohistochemical study documents our experience with five PBPFs in newborns and children up to 11 years of age at diagnosis. The tumors were either endobronchial or intraparenchymal in location. A uniform population of interlacing bundles and sheets of densely arranged spindle cells with variable mitotic activity was observed microscopically in each case. Ultrastructurally, the cells had the features of fibroblasts and vimentin was the only immunohistochemical marker identified. Despite the disturbing pathologic findings, the four children with more than 1 year of follow-up have survived well 4 to 9 years after surgical resection. Our results are compared with the 21 cases of PBPF reported in the literature and the differential diagnosis is discussed.

Bronchial Neoplasms↗
PubMed1981

Age-related increases in mitogenic responses and natural immunity to a syngeneic fibrosarcoma in rats.

An increase in natural (innate) immunity with age (through 65 weeks) of NBR rats to a syngeneic methylcholanthrene-induced fibrosarcoma (MCA) is described. This increase is characterized by the appearance of spontaneous tumor regressor animals and an increase in the incidence of tumor non-takes by rats 45 weeks of age and older when compared to younger animals. Age-related changes were observed in the in vitro proliferative responses of normal unfractionated and nylon wool fractionated spleen cells to Con A, PHA and irradiated MCA tumor cells. Certain of these different proliferative responses either increased and/or decreases independently at different ages. Relative to normal spleen cell proliferative responses, tumor progressors have decreased proliferative responses and tumor regressors display increased proliferative responses. The significance of this in light of current aging research is discussed.

Aging↗
PubMed1984

Fibrosarcoma complicating irradiated pituitary adenoma.

Eight years after radiation therapy (5000 rads of 60Co) for a pituitary adenoma, a patient developed a sellar fibrosarcoma. The tumor had an aggressive growth pattern: it infiltrated the optic nerve, sphenoidal air sinus, hypothalamus, and both cavernous sinuses, where compression of the left internal carotid artery resulted in a massive hemispheric infarction. Surgery was ineffective in arresting rapid growth of the lesion; death occurring 5 months after onset of symptoms.

Adenoma, Chromophobe↗
PubMed1980

Fibrosarcoma of kidney.

A case of fibrosarcoma of the kidney is presented. Clinical and radiologic features are discussed. The arteriographic features of this tumor are indistinguishable from adenocarcinoma of the kidney. Microscopically, this tumor may be confused easily with leiomyoma or leiomyosarcoma, Special staining techniques with van Gieson and Mallory trichrome stains and electron microscopy help establish diagnosis.

Adenocarcinoma↗
PubMed1985

Fibrosarcoma of epididymis.

We present a case of fibrosarcoma of the epididymis occurring in a sixty-year-old man. While review of the literature has failed to determine an exact number of such cases reported, we believe the number is small. We discuss the treatment options and prognosis for these patients.

Epididymis↗
PubMed1990

Ovarian fibrosarcoma associated with Maffucci's syndrome.

Maffucci's syndrome, a congenital condition of generalized mesodermal dysplasia, is most often associated with multiple enchondromas and soft tissue hemangiomas or lymphangiomas. This case report describes the development of an unusual ovarian fibrosarcoma and subsequent ovarian adenofibroma in a young woman with the syndrome. The importance of aggressive surveillance in this and similar orthopedic syndromes is stressed.

Adenofibroma↗
PubMed1975

Fibrinolytic activity in a human fibrosarcoma cell line and evidence for the induction of plasminogen activator secretion during tumor formation.

Seven clones were isolated from the HT1080 human fibrosarcoma cell line using a fibrinagarose overlay technique. Three of these clones induced lysis of the fibrin overlay, whereas four did not. The extracellular and intracellular levels of protease were then measured using 125I-fibrin plates incubated with acid-treated human serum. The extracellular protease can be directly assayed in the medium from cells incubated with 10% fetal calf serum. Although there were large differences in the amounts of protease secreted by these two sets of clones, the intracellular levels of protease were similar. No significant differences were found between the abilities of the cells to grow in soft agar or as tumors in immunosuppressed hamsters. However, cells grown from tumors derived from all the low secretors of protease showed an increase in the amount of protease secreted. It appeared, therefore, that the secretion of protease might be selected for or induced during tumor growth. Further detailed studies with one of the low secreting clones (clone E) suggested an inductive rather than a selective mechanism for this increase in extracellular plasminogen activator.

Cell Line↗
PubMed1982

Regulation of prostaglandin synthesis mediated by thrombin and B2 bradykinin receptors in a fibrosarcoma cell line.

The murine fibrosarcoma cell line HSDM1C1 synthesizes prostaglandin E2 in response to thrombin and bradykinin, two products of the coagulation pathway. These physiologic effectors interact with two independent cell-surface receptor systems whose properties we have characterized. HSDM1C1 cells possess a B2 bradykinin receptor, a type more sensitive to native bradykinin than to related peptides, including Met-Lys- and desArg9-bradykinin. A period of bradykinin desensitization follows the initial response. Recovery occurs within 1 hr by a process independent of serum factors. The thrombin-mediated pathway differs in several respects. The maximum amount of prostaglandin E2 synthesized is 40% lower. Prolonged desensitization of the thrombin response occurs after an initial exposure; recovery requires at least 3 hr and depends strictly on the presence of serum. Antithrombin III and hirudin, two proteins that specifically inactivate thrombin, act in serum-free medium to relieve thrombin desensitization. Thrombin's prolonged desensitization thus suggests a persistent ligand-receptor association. The expression of receptor-mediated prostaglandin synthesis governed by multiple physiologic effectors in the same cell may reflect environmental conditions, such as the relative proportions of each effector and the presence of exogenous factors that modulate the ligand-receptor interaction.

Animals↗
PubMed1983

Regulation of fibronectin biosynthesis by glucocorticoids in human fibrosarcoma cells and normal fibroblasts.

When treated with the synthetic glucocorticoid dexamethasone, HT1080 human fibrosarcoma cells show changes in morphology, adhesion, and the extracellular matrix. Dexamethasone treatment results in a tenfold increase in the rate of fibronectin biosynthesis in HT1080 cells and a twofold increase in untransformed, normal human fibroblasts. Maximal induction levels are attained within one cell generation, while decay of the response requires several cell cycles. Pulse-chase studies showed that most of the newly synthesized fibronectin is secreted into the medium. The glucocorticoid antagonist, RU-486, blocks the dexamethasone-induced changes but does not alter the basal rate of fibronectin production. Therefore, fibronectin biosynthesis appears to be controlled by two distinct mechanisms--one, regulating basal rates of fibronectin production, which is transformation-sensitive and glucocorticoid-independent; and another, which is mediated by the glucocorticoid receptor, resulting in elevated rates of fibronectin biosynthesis upon dexamethasone treatment both in normal fibroblasts and in HT1080 cells.

Cells, Cultured↗
PubMed1987

Activated N-ras controls the transformed phenotype of HT1080 human fibrosarcoma cells.

To investigate whether the activated N-ras oncogene of HT1080 human fibrosarcoma cells contributes to the expression of the transformed phenotype, we have isolated flat revertants. In two independent revertant lines, an increase in chromosomal ploidy occurred without a concomitant increase in the number of copies of the N-ras transforming allele. Immunoprecipitation confirms that the level of the mutant N-ras p21 gene product in the revertants is correspondingly lower than in HT1080. Analysis of sporadic tumors derived from the revertant cells reveals an increased dosage of the transforming allele. The revertants also retransform after transfection of cloned activated ras oncogenes. These results imply direct participation of an N-ras oncogene in maintaining the transformed phenotype of a human tumor cell line.

Alleles↗